Thoracotomy is often performed in patients withpreexisting lung disease such as lung cancer and chronicobstructive pulmonary disease. It is associated with thepotential for severe pain, further impairment of lung function,delayed recovery and the occurrence of chronic pain(Perkins & Kehlet, 2000; Senturk et al, 2002;Ochrochet al 2002).
Chronically, pain can last for months to years, and even low levels of pain can decrease function. Other than pain syndromes associated with limb amputation, pain after thoracic surgery may be the most recognized pain syndrome associated with a specific surgery. (Dajczman et al 1991; Landreneau et al 1994;Bertrandetal,l996).
Many methods of pain management, have beentried with varied success: intercostal nerveblock, intrapleural analgesia , cryoanalgesia ,lumbarepidural , thoracic epidural paravertebral block, intravenous narcotics , intrathecal or epiduralnarcotics, nonsteroidal anti-inflammatory drugs(NSAIDS) , and transcutaneous nerve stimulation .
Acute postthoracotomy painSevere acute pain after thoracotomy caused by retraction,resection, or fracture of ribs, dislocation of costovertebraljoints, injury of intercostal nerves, and further irritation ofthe pleura by chest tubes is a normal responseto all theseinsults . Acute pain after video-assisted thoracoscopicsurgery is considered less severe.
Suboptimal management of pain after thoracotomy (orafter video-assisted thoracoscopic surgery in patients whohave severely limited respiratory reserve) has majorrespiratory consequences. Inspiration is limited bypain,which leads to reflex contraction of expiratorymuscles and consecutively diaphragmatic dysfunction(decreased functional residual capacity andatelectasis, shunting, and hypoxemia).
Chronic postthoracotomy painPostthoracotomy pain syndrome (chronic postthoracotomy painor postthoracotomy neuralgia, PTPS) is defined by theInternational Association for the Study of Pain as ‘‘pain thatrecurs or persists along a thoracotomy incision at least twomonths following the surgical procedure.’’ In general,it is burning and stabbing pain with dysesthesia and thus sharesmany features of neuropathic pain. PTPS is acknowledgedincreasingly by anesthesiologists and surgeons alike .
Prevalence of postthoracotomy pain Despite a commonly held belief that postthoracotomy painis transient, there is no evidence that the pain experience decreasessignificantly over time. For example, incidence of long-termpostthoracotomy pain has been reported to be 80% at 3 months,75% at 6 months, and 61% at 1 year after surgery; the incidence ofsevere pain is 3% to 5%, and pain that interferes with normal life isreported by about 50% of patients.
In one study, 66% of the patients who had PTPSreceived treatment for pain . In another study, morethan 70% of the patients who had PTPS receivedthree or more of the treatment modalities andregimens that have been reported to be of value.More than 50% needed.
Other mechanismsStudies suggest that personality traits are strong modulatory factorsin the overall experience of postthoracotomy pain. Preoperativeanxiety seems to play a major role. The costochondral andcostovertebral junctions may be disarticulated because of extensiverib retraction, and ipsilateral shoulder disability also is common asa result of the division of serratus anterior muscles and latissimusdorsi. Injuries to the muscles responsible for moving the shoulderas well as insufficiently treated pain lead to inadequaterehabilitation and may produce frozen shoulder.
Epidural analgesiaTechniqueMedian or paramedian approach.Asleep versus awake technique
The Horlocker TT and colleagues stronglydiscourage insertion of thoracic epidural cathetersin anesthetized/paralyzed patients in all but therarest circumstances (for example, a thoracoscopicsurgery that is converted to a thoracotomy in apatient who has a severelycompromised respiratory reserve, when extubationis most likely to fail) and then only by veryexperienced operators
. Similarly,others also state that ‘‘techniques abovethe termination of the cord . should be avoided (inanesthetized patients)’’ In addition, when epiduralanatomy was examined by cryomicrotome sectionin humans, it was found that the ligamentumflavum is more frequently discontinuous at thethoracic level than at the lumbar level further.
. Outcome Some strongly suggest improved outcomes with use ofepidural catheters, whereas others have found noimprovement.In general, it is difficult to compare thesestudies. Some authors looked at the effects of differentanalgesia techniques on long-term postthoracotomy pain, whereas others investigated the effect of epiduralanalgesia in the reduction of postoperative myocardialinfarction via a meta-analysis .
Similarly, cumulative meta-analysis of randomized, controlled trialsthat evaluated the comparative effects of postoperative analgesictherapies on pulmonary outcome concluded that ‘‘epidural paincontrol can significantly decrease the incidence of pulmonarymorbidity’. Some randomized studies, however, looked at epiduralversus intravenous (or intramuscular)on-demand analgesia and, notsurprisingly, found a superior outcome with the epidural group.Overall, it seems to be important not only whether the patientreceived epidural analgesia, but also how the epidural was managed.
Intercostal nerve block. The simplest method is a single injection of local anesthetics inmultiple intercostal nerves before closure of a thoracotomy incisionSingle-shot intercostal nerve blocks with local anesthetic generally donot provide effective long-term analgesia, however, and frequentlymust be repeated. A longerlasting method involves continuous infusionof local anesthetics for several days through an indwelling catheterplaced in a subpleural/extrapleural pocket, allowing the local anestheticto diffuse to the nerves. Most surgeons use this approach forthoracoscopic surgeries, although others argue thatan intercostal catheter is equivalent to epidural analgesia combinedwith patient-controlled analgesia
As can be seen in Fig. 1, an intercostal nerve block by a needle insertedperpendicular to the skin in the posterior axillary line does not cover pain inthe more posterior parts of the back. In addition, if a chest tube is not inplace, the risk of pneumothorax from the block needs to be considered.
Paravertebral nerve blockSome authors consider paravertebral block nearlyequivalent to epidural analgesia, without thedetrimental effects of bilateral sympathetic blockade. Itis somewhat surprising that this technique is not morewidespread, possibly because it has becomereintroduced into clinical practice only recently.
Technique of Thoracic Paravertebral BlockSeveral different techniques exist for TPVB.1- The classical technique2- The Use of nerve Stimulator.3- Ultrasound guidance.(Karmakar & Mano.,2001)4- surgical approach.
Landmarks The following surface anatomy landmarks are used toidentify spinal levels and estimate the position of the transverseprocesses: Spinous processes (midline). Tips of scapulae (corresponds to T7). Paramedial line 2.5 cm lateral to the midline.
The Use of a Nerve Stimulator forThoracic Paravertebral Block Ultrasound guidance in Thoracic Paravertebral Block
Pre-emptive analgesia and thoracotomySome of the mechanisms for the development ofallodynia and hyperalgesia are well known. Theconcept of sensitization has led to an increased effort tocontrol acute pain by a more or less total afferentblockade, with the goal of reducing the development ofpostthoracotomy pain.
Pre-emptive analgesia is intended to prevent theestablishment of central sensitization caused byincisional and inflammatory injuries. Evidence frombasic research has indicated that analgesic drugs aremore effective if administered before, rather thanafter, a noxious stimulus. The benefit of pre-emptiveanalgesia has been supported by some clinical studiesusing local anesthetics opioids, and NSAIDS.
Previous studies comparing the effects of preoperative andpostoperative epidural block in abdominal surgery have failed todemonstrate any benefit of pre-emptive analgesia [78,79]. This lackof benefit was attributed in part to the less discrete, visceral nature ofpain after abdominal surgery. Thoracotomy produces high-intensitynoxious stimuli sufficient to cause central sensitization [84,85], andthe area of postthoracotomy pain is more discrete, largely restrictedto the site of surgery. Hence, any benefit of pre-emptive epiduralanalgesia should, theoretically, be more apparent in thoracic surgerythan in abdominal surgery.
Some recent studies have shown beneficial effects(both immediate and late) when pre-emptiveanalgesia (nerve blockade either by epidural orintercostal nerve block) was begun before thesurgical incision [52,85,88,94].Other researchers, however, have found marginal orno benefits even when a multimodal approach wasused
Shoulder painThe shoulder pain reported by patients who haveundergone thoracotomy is mostly referred pain and is notcovered by the epidural analgesia.Most surgeons would agree that shoulder pain is a majorpostoperative pain problem that deserves special attention.
More than 75% of thoracotomy patientsreport constant severe ache in the ipsilateralshoulder after surgery. This pain is relativelyresistant to intravenous opioids and is onlypartially relieved by NSAIDs.
Postulated mechanisms include transection of a majorbronchus, ligamentous strain from malposition orsurgical mobilization of the scapula, pleural irritationcaused by the thoracostomy tube, or referred pain fromirritation of the pericardium or mediastinal anddiaphragmatic pleural surfaces.
It seems that the main origin of shoulder pain may be referred painvia the phrenic nerve (blocked by periphrenic infiltration andinterscalene brachial plexus block) with contributions frompositioning and surgery (coracoid impingement syndrome andcoracoclavicular ligament strain), which is partially relieved by theuse of NSAIDS. and acetaminophen. Some patients who receivedphrenic nerve infiltration still reported pain, perhaps because ofanatomic variations in the emergence of the sensory fibers from thephrenic nerve reaching the fibrous pericardium and parietal layers ofthe pleura.
The most effective management strategy would bemultimodal, consisting of acetaminophen (pre-emptive and regularly), NSAIDS if notcontraindicated, and infiltration of the phrenic nervewith a long-acting local anesthetic.
In summary, it seems that the most logical explanation for the failureof pre-emptive analgesia has two components: first, afferent impulseblockade should be complete, which is impossible given the varietyof incoming stimuli, and should also last for at least several dayspostoperatively. Secondly, a complete ‘‘humoral blockade’’ would benecessary, because it has been shown that circulatingproinflammatory cytokines lead to central cycloocygenase-2induction (eg, interleukin-1b–mediated induction of cycloocygenase-2 in the central nervous system contributes to inflammatory painhypersensitivity).
PATHOPHYSIOLOGY OF TISSUE DAMAGEAFTER THORACOTOMY1. Rib retraction and intercostal nerve damage:2- Intercostal nerve damage and type of thoracotomy:3- Intercostal nerve damage and closure of thoracotomy with pericostal sutures: